A toilet that rocks or wobbles on the floor isn't just annoying — left unfixed, it can crack the pan, break the seal at the floor waste, and eventually cause water damage or sewage leaks underneath. The good news is that in many cases the fix is straightforward and a confident DIYer can tackle it without calling a plumber.
Why Is My Toilet Rocking?
Before grabbing your tools, it helps to understand what's causing the movement. The most common culprits are:
- Loose or corroded floor bolts (pan bolts) – The bolts that secure the toilet pan to the floor have worked loose or rusted away.
- Worn or missing pan collar – The plastic or rubber collar connecting the toilet to the floor waste has deteriorated.
- Uneven floor – Tiles, vinyl, or timber can be uneven, leaving the toilet base unsupported on one side.
- Cracked toilet base – Less common, but a hairline crack in the porcelain can cause movement.
- Rotted subfloor – In older homes, especially those with timber floors, moisture from a slow leak can rot the subfloor beneath the toilet.
Start by gently rocking the toilet side to side and front to back to get a sense of where the movement is coming from.
What You'll Need
Step-by-Step: Fixing a Rocking Toilet
1. Check and Tighten the Pan Bolts
Most toilets are secured to the floor with two bolts, usually hidden under plastic caps at the base of the pan. Prise off the caps with a flathead screwdriver. If the nuts underneath are loose, try tightening them with an adjustable spanner — but do not overtighten, as this can crack the porcelain. Tighten gradually, alternating sides, until the toilet feels firm.
If the bolts spin freely or are corroded, they'll need replacing. Turn off the water supply at the isolating valve (usually on the wall behind the toilet), flush to empty the cistern, and disconnect the water supply hose. You may then need to lift the toilet to access and replace the bolts and pan collar.
2. Use Plastic Shims for an Uneven Floor
If the bolts are tight but the toilet still rocks, the floor is likely uneven. Slide plastic toilet shims under the base where the gap is. Tap them in gently until the toilet sits firm and level. Once you're happy with the fit, score off the excess shim with a utility knife.
3. Seal the Base
Once the toilet is stable, run a bead of sanitary silicone around the base where it meets the floor. Leave a small gap at the back — this allows any water from a future leak to escape visibly rather than pooling unseen underneath. Smooth the silicone with a wet finger and allow it to cure as per the manufacturer's instructions.
4. Inspect the Pan Collar and Floor Waste
If you've had to lift the toilet, inspect the pan collar (the fitting that connects the toilet outlet to the floor waste). In New Zealand, most toilets connect via a P-trap or S-trap arrangement to a floor or wall waste. A cracked or deteriorated collar should be replaced. Replacement collars are available at PlaceMakers and most plumbing suppliers.
Important: Replacing a pan collar involves disconnecting the toilet from the drain. Under the Plumbers, Gasfitters and Drainlayers Act 2006, work that involves connecting or disconnecting sanitary fixtures from the drainage system is restricted work and must be carried out by a licensed plumber or drainlayer. If you're unsure whether your repair crosses this line, check with the PGDB or call a licensed tradesperson.
5. Check the Subfloor
If you notice soft or spongy flooring around the toilet base, or if there's a musty smell, the subfloor may have been damaged by a slow leak. Press the floor around the toilet with your foot — any give or bounce is a warning sign. This will need assessment by a builder or plumber before the toilet is refitted.
When to Call a Professional
Call a licensed plumber (find one at tradedirectory.co.nz) if:
- The toilet needs to be disconnected from the drain to fix the problem — this is restricted work under NZ law.
- You find signs of subfloor rot or structural damage.
- The toilet pan is cracked and needs replacing.
- The floor waste or drain itself appears damaged or misaligned.
- You're not confident working around the toilet's water supply and waste connections.
A licensed plumber can also certify their work, which matters for insurance purposes and if you ever sell your home. Check that your plumber is registered with the PGDB.
A Note on NZ Building Regulations
Simple repairs like tightening bolts or shimming a toilet generally don't require a building consent. However, if the repair involves replacing drainage components or significant structural work to the floor, it may. When in doubt, check with your local council. The MBIE Building Performance website has useful guidance on what work requires consent and what falls under Schedule 1 exemptions.
Safety Reminder
Always turn off the water supply before working on your toilet. Wear gloves when handling any components near the waste outlet, and wash your hands thoroughly afterwards.
Master Plumbers
